1. Field of the Invention
This invention generally relates to a bicycle front derailleur. More specifically, the present invention relates to a bicycle front derailleur that smoothly and reliably shifts a bicycle chain between the front sprockets of the drive train.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle as well as the frame of the bicycle. One part of the bicycle that has been extensively redesigned is the front derailleur. A front derailleur is typically mounted onto the bicycle frame adjacent to the front sprockets.
Generally, a front derailleur includes a fixed member non-movably secured to a bicycle frame, and a movable member supported to be movable relative to the fixed member. Typically, the fixed member is a tubular clamping member that is secured to the seat tube. Alternatively, the fixed member is sometimes coupled to the bottom bracket. The movable member typically has a chain guide with a pair of cage plates for contacting and moving a chain between the front sprockets. The movable member is usually biased in a given direction relative to the fixed member by a spring. The movable member is usually moved relative to the fixed member by pulling and/or releasing a shift control cable that is coupled to the front derailleur. The movable member and the fixed member usually are interconnected through pivotal links.
One problem with typical front derailleurs is that the various members experience a variety of forces from the control element (wire), links, biasing member and chain (resistance). These forces can cause stresses and/or deformation to the various members, and thus, smooth shifting can be adversely affected. Another problem with typical front derailleurs is that they can be relatively heavy in order to reduce stresses and/or deformation of the various members. Moreover, these prior art derailleurs can be relatively complicated and expensive to manufacture and assemble.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle front derailleur that overcomes the above mentioned problems in the prior art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.